cpuidle_cooling_runtime(9)

💅 cpuidle_cooling_runtime(9) — like, the runtime computation one 🧮✨

okay bestie, so this is a page from the Kernel API Manual (yes, that manual) and it's all about cpuidle_cooling_runtime. It's giving "small function, big math energy" and honestly? We're obsessed. 🫶

---

✨ NAME ✨

cpuidle_cooling_runtime — Running time computation 💫

---

🌸 SYNOPSIS 🌸

unsigned int cpuidle_cooling_runtime (unsigned int idle_duration_us ,
       unsigned long state );

like, that's the whole signature. no cap. 👑

---

🎀 ARGUMENTS 🎀

• idle_duration_us — the CPU idle time you wanna inject, measured in microseconds. that's the vibe. ⏱️
• state — a percentile based number. iykyk. 🔢

---

🦋 DESCRIPTION 🦋

so here's the tea ☕ — the running duration gets computed from the idle injection duration, and that idle injection duration is fixed. periodt.

• if we hit 100% of idle injection ratio, that means the running duration is zero. like, gone. 💀
• if we've got a 50% ratio injection, that means we have equal duration for idle and for running duration. balanced. as all things should be. ⚖️

the formula is deduced as follows, and yes we're putting it in a code block because it's iconic:

running = idle x ((100 / ratio) - 1)

but for precision purpose for integer math, we use this one instead — don't @ me, integer math is a whole situation 😭:

running = (idle x 100) / ratio - idle

for example! if we have an injected duration of 50%, then we end up with 10ms of idle injection and 10ms of running duration. math ate that fr fr. 🔥

---

👑 RETURN 👑

an unsigned int for a usec based runtime duration. so like, a number in microseconds. slay. 💅

---

🌈 SEE ALSO 🌈

• Kernel file ./drivers/thermal/cpuidle_cooling.c struct cpuidle_cooling_device(9)
• cpuidle_cooling_get_max_state(9)
• cpuidle_cooling_get_cur_state(9)
• cpuidle_cooling_set_cur_state(9)
• __cpuidle_cooling_register(9)
• cpuidle_cooling_register(9)

like, go read the whole thermal family bestie, they're all main characters. 🧚

---

okay that's the whole page!! huge shoutout to ./drivers/thermal for being the source, October 2026 for the date, and cpuidle_cooling_runtime(9) for being the moment. mwah 💖✨🎀🦋